A HFC network consists of a headend office, distribution centre, fibre nodes, and network interface units. The headend office receives information such as television signals, Internet packets, and streaming media, then delivers them through a fibre ring to distribution centres. The distribution centres then send the signals to distribution nodes, which convert the optical signals to electrical signals and redistributes them on coaxial cables to residents’ homes where network interface units send the appropriate signals to the appropriate devices.
Approximately 2 million homes in Melbourne and Sydney are passed by HFC networks owned by Telstra and Optus. Some parts of these networks are currently being upgraded to higher bit rate, but they are highly asymmetric and their upload capability is severely limited, particularly if all users try to download data at the same time. Under the original NBN plan broadband access over these HFC networks would be decommissioned and replaced with FTTP.
The Coalition plan was to re-use both the Telstra and Optus networks. Their plan stated:
Broadband over HFC provides much of the world’s very fast broadband today, and there is a clear upgrade path to 300 megabits per second. The value of network technologies, which increase data rates over existing networks, is they avert the need to upgrade or replace ‘last mile’ lines to every home and business. This is expensive because it is both disruptive to residents, businesses and public amenities and labour intensive; regrettably.
After lengthy negotiations, Telstra and Communications Minister Malcolm Turnbull announced on 14 December 2014 the re-signing of the Telstra deal, which will see NBN Co continue to pay Telstra $5 billion in infrastructure payments, $4 billion in disconnection payments and $2 billion in Commonwealth agreements.
NBN Co will take over ownership of the HFC for the purpose of using them where it sees fit in for its multi-technology NBN rollout.
Telstra will remain able to use the HFC networks to serve its retail and wholesale customers while the assets are progressively transferred to NBN Co. Licenses for the HFC network will be in place until Telstra no longer provides pay TV services.
After insisting that Optus’s old hybrid fibre-coax infrastructure could be used for the NBN, the government-owned company announced on 28 September 2016 that the network would be dumped from its plans.
The change of heart is even more embarrassing for the NBN because last November the company dismissed concerns about the state of the Optus infrastructure after a leak exposed its dire condition. That leak led to the politically-charged AFP raids on retiring Labor senator Stephen Conroy, the former minister in charge of the NBN, and his office, in May as the federal election got underway
In November 2017 the NBN Co is warned of a delay of between six and nine months in the rollout of its network using Telstra's pay TV cables. Nearly 3 million people are ultimately slated to get the NBN via Hybrid Fibre Coaxial (HFC) connections.
In Feruary 2018 NBN's half yearly result showed an increase of $450 million in costs to the HFC network.
Sam Varghese wrote in ITWIRE on 28 November 2018:
For months now, we've been told that fast broadband would be arriving sooner because of the change in technology that the Coalition Government decided upon, with HFC cable and fibre-to-the-node being the saviours of the project. Now that dream is unravelling.
The brakes have been well and truly slammed on by the NBN Co, with delays of six to nine months in getting any HFC connections up.
The Telstra HFC cable network is being shared by the NBN Co, Telstra and Foxtel; the NBN signal travels at a low frequency, the other two at higher frequencies. Apparently, at lower frequencies the signal does not travel all that well. The equivalent of bandages will have to be applied. But the long-term solution will be to replace cable with fibre.
What was to have been a marathon — fibre-to-the-premises for 93%, satellite and fixed wireless for the rest — was attempted to be turned into a sprint by the agile and innovative Malcolm Turnbull. Alas, the dream of the silver-haired visionary now seems to be dead.